Many latch mechanism proposals have been made for securing vehicular doors to the "B" or "C"-Pillars. (Two of such proposals include those shown in U.S. Pat. Nos. 4,358,141 and 4,538,845.)
Latch mechanism proposals normally include:
(a) a resiliently biased ratchet carrying a recess for receiving a striker (carried by the "B" or "C"-Pillar), the ratchet pivotable from an open position for receiving the striker to a closed position for locking the door to the "B" or "C"-Pillar,
(b) a pawl for locking the ratchet in a locked position,
(c) a release lever for releasing the pawl for releasing the ratchet to pivot to the open position (by for example lifting the inside or outside release handle) and
(d) a locking lever for precluding a release lever from releasing the pawl.
Because of the downsizing of cars, collisions of the smaller vehicles with other vehicles may have greater structural deformation of the component parts making up these vehicles, than the larger ones and more serious consequences may result. In some instances, the latch mechanism securing the door to the striker detaches from the striker and the door opens.
During normal use of the vehicle when driving, the body of the car flexes and thus the components flex relative to one another. Flexing occurs between the striker and the latch housing in which it is secured.
When latching the striker in a housing, four types of movement may occur and must be accounted for when securing the striker:
(a) vertical motion of the striker relative to the latch housing (up and down)
(b) lateral motion of the striker relative to the housing (into and out of the body cell)
(c) forward and backward motion of the striker relative to the housing and
(d) torsional movement of the striker relative to the latch housing.
If any of these types of motion are not accounted for, an "inferior" design will occur.
In the most common vehicle door latch design wherein the striker comprises a substantially cylindrical shank having a head of extended diameter at the end thereof, the head portion and shank sliding into a horizontally extending slot disposed within the door closed at one end, the ratchet encouraged to rotate by said striker, thereby engaging the shaft behind the head of the striker and thereby preventing the striker from exiting the slot. However, the latch does not rigidly hold the door closed as there is a certain amount of free play resulting in rotating of the door in time. Such rotational forces are usually not in a single plane, and the tendency during a collision is for either the head of the striker to partially or totally shear away from the locking engagement with the ratchet or the ratchet will bend, buckle and twist, thereby disabling the mechanism. Examples of such vehicle door locks may be seen in U.S. Pat. Nos. 3,674,296; 4,130,308; 4,357,039; 4,358,141 and 3,367,699.
In an effort to compensate for the rotation of the ratchet relative to the striker in a collision it is known to provide a striker having a structure which is tapered in one axis. Such a "wedge shaped" striker is mounted on a vehicle pillar. The wedge shape is generally horizontally inclined with the smaller cross section of the wedge leading the advance of the striker into a slot for engagement thereat with a ratchet. An example of a wedge shaped striker may be seen in U.S. Pat. Nos. 4,165,112 and 4,219,227. As appears from U.S. Pat. No. 4,219,227 a ratchet engages a depression in the wedge shaped striker. As appears from U.S. Pat. No. 4,165,112 the striker has a hole through it, through which a leg of a U-shaped ratchet passes when the mechanism is engaged. It will be appreciated by those skilled in the art that such an arrangement would tend to prevent rotation of the striker in relation to the housing therefor.
Further it will be appreciated by those skilled in the art that proper engagement of the ratchet with the hole in the striker is very necessary. To this end, such a mechanism requires careful design and installation which ensures in continuous use that when the door is closed, the ratchet will be aligned with the hole in the striker for engagement therewith. Various bumpers, guides and elastomeric devices have been proposed to assist such an alignment. In U.S. Pat. No. 4,219,227 and in an older U.S. Pat. No. 3,858,919 a cone shaped pin is mounted in the slot receiving the door striker. The door striker has a cone shaped recess which slideably fits over the cone shaped pin when the door striker is engaged in the slot for locking. It will be appreciated by those skilled in the art that while the foregoing mechanisms may provide for proper alignment with the aid of bumpers, elastomeric devices and shims during installation and further such a device may assist in reducing rotation in a plane perpendicular to the axis of the door striker, the mechanism will still permit longitudinal separation of the striker from the slot in a longitudinal direction in for example the axis of the striker extending away from the pillar generally in the lengthwise direction of the car. Furthermore, because of the design tolerances required it is likely that any deformation of the locking mechanism components concomitant with a collision will cause jamming, resulting in difficulty for a passenger to release the locking mechanism in order to leave the car.
It is known in the art to provide an engagement between a striker and a slot for receiving the striker which will resist the longitudinal separation of the striker from the slot for receiving same. For example, U.S. Pat. Nos. 1,192,733 and 2,100,591 disclose a "hook shaped" striker. The hook or projection of the striker fits into a slot which is generally U-shaped and surrounds the hook, thereby preventing longitudinal separation. In the latter U.S. Pat. No. 2,100,591, a bolt slides internally of the U-shaped slot for engaging a corresponding aperture in the hook. In this manner, the hook cannot slide out of the recess.
In U.S. Pat. No. 2,758,864 a locking mechanism is disclosed wherein the striker is generally T-shaped in cross section and may be slidingly keyed into a slot having the same T-shaped cross section. The leading edge of the striker having a T-shaped cross section is formed with a cam surface for displacing a spring biased latch bolt which may slideably enter the slot. When the door is closed the cam surface of the striker raises the latch bolt. The latch bolt passes over the striker to the back of the striker and blocks its exit from the slot. It will be appreciated by those skilled in the art that such an arrangement is similar in principle to the traditional arrangement of a striker pin engaging a pivotable ratchet which once engaged blocks the exit of the striker pin from the slot.
In United Kingdom Patent 239,691 there is provided a latching mechanism for use in a motor vehicle wherein the "striker" slidingly engages a slot in a latch housing. The striker is of a generally T shaped cross-section--the head of the striker is tapered in two directions, being wider at the base than the leading edge and has a transverse taper from the base at the back, to the front. The neck of the striker is also tapered, being wider proximate the base than the leading edge. The slot is tapered in two directions comprising a "V" shaped taper matching that of the neck of the striker and a transverse taper matching the transverse taper of the head of the striker. The combination of the transverse taper of the striker head and the transverse taper of the slot draws the striker and the latch housing together when placed in engagement. It will be appreciated by those skilled in the art that the transverse taper is not symmetrical. Exact alignment of the striker with the slot is therefore required during design and installation thereof.
In U.S. Pat. No. 4,466,645 a U-shaped striker is disclosed having a part covered by a mould-formed plastics material, the portion of which carried at the juncture of one corner of the horizontal connector and leg which is pushed into a door latch being thicker, to present a columnar shape.
It is also desirable to minimize the closing efforts of the striker into the latch housing. In some instances where rubber or elastomeric bumpers are provided in the striker receiving recess of the latch housing, the engagement of the striker with the walls and bumpers of the striker receiving recess increases the effort to insert the striker deeper into the recess because of the jamming effect. This is magnified where there exists wide ranges of tolerance between the striker and wall and bumpers in the recess.
In my Canadian Application Serial Number 525,664, I disclosed tapered strikers.
It is therefore an object of this invention to provide an improved latch housing and components therefor.
It is a further object of the invention to provide an improved latch housing - striker combination which has enhanced safety characteristics should an accident occur.
It is still a further object of the invention to provide a quieter latch housing and striker combination.
It is a further object of the invention to provide a latch housing - striker combination which minimizes the closing effort of securing the striker in the latch receiving recess of a latch housing.
It is a further object of the invention to provide support against door sag in the door "ajar" position (or "secondary position").
Further and other objects of the invention will be realized by those skilled in the art from the following summary of the invention and detailed description of embodiments thereof.